AutoCodes – Buick – P0686 Buick

P0686 Buick Code - Engine Control Module Power Relay Control Circuit Low

Quick Answer

The powertrain relay is a normally open relay. Common causes include Weak battery, Low voltage while cranking, Faulty Engine Control Module (ECM) power relay. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0686 Buick indicates Engine Control Module Power Relay Control Circuit Low.
Common causes: Common causes include Weak battery, Low voltage while cranking, Faulty Engine Control Module (ECM) power relay.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,767

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 18, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0686 Buick Description

The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The Engine Control Module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an Output Driver Module (ODM). The ODM output control is configured to operate as a low side driver for the powertrain relay. The ODM for the powertrain relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the ECM, and to several additional circuits.

OBDII Code P0686 Buick - Engine Control Module Power Relay Control Circuit Low - AutoCodes.com — P0686 Buick Code - Engine Control Module Power Relay Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0686 Buick?

Weak battery
Low voltage while cranking
Faulty Engine Control Module (ECM) power relay
ECM power relay harness is open or shorted
ECM power relay circuit poor electrical connection
Blown ECM fuse
Faulty ECM

How to Fix the DTC P0686 Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0686 Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0686 Buick code?

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Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0686 Buick Code

1. What are the common symptoms of OBDII code P0686 in a Buick?

- Common symptoms include rough idling, stalling, poor engine performance, and difficulty starting the vehicle.

2. What does the OBDII code P0686 Buick indicate?

- This code indicates a problem with the Engine Control Module Power Relay Control Circuit being low.

3. What are the possible causes of the P0686 code in a Buick?

- Possible causes include a faulty power relay, damaged wiring or connectors in the power relay circuit, or a malfunctioning Engine Control Module (ECM).

4. How can I diagnose the P0686 code in my Buick?

- Diagnosing the issue involves checking the power relay, inspecting the wiring and connectors for damage, and testing the ECM for proper functioning.

5. Can I drive my Buick with the P0686 code present?

- It is not recommended to drive the vehicle with the P0686 code present, as it can lead to further damage to the engine or other components.

6. How can I repair the P0686 code in my Buick?

- Repair options include replacing the faulty power relay, repairing any damaged wiring or connectors, or replacing the Engine Control Module if necessary.

7. Will resetting the trouble codes make the P0686 code disappear?

- While resetting the trouble codes may temporarily clear the code, it is important to address the underlying issue causing the code to prevent it from reoccurring.

8. How much does it typically cost to repair the P0686 code in a Buick?

- The cost of repair can vary depending on the specific cause of the issue, but it may range from $100 to $500 or more, including parts and labor.

9. Can a DIY enthusiast fix the P0686 code in a Buick?

- Depending on the individual's mechanical skills and access to tools, some DIY enthusiasts may be able to diagnose and repair the issue themselves, especially if it involves replacing a power relay or checking for damaged wiring.

10. Is it necessary to visit a dealership for repairs related to the P0686 code in a Buick?

- While visiting a dealership is an option, independent auto repair shops or experienced mechanics can also effectively diagnose and repair the P0686 code in a Buick.